5 day late period, headache, shoulder pain, dozing off-pregnant?

My ex girlfriend came to me yesterday saying her period hadn't come yet and she had been dozing off in class that day. Today she also complained of shoulder pain and headaches. She is about 5 days late I assume, and yes we did have sex multiple times, but each time we used a condom and there was no recollection of slips or breakages. We just broke up two days ago. Should we be worried?